Toroidal variable-speed drive unit

ABSTRACT

A toroidal variable-speed drive unit includes at least one axial offset transmission, at least one actuating member, pivotable supporting journals, and rollers arranged on the pivotable supporting journals which are coupled to one another by the at least one axial offset transmission and can be supported on the at least one actuating member, wherein the rollers are arranged between the actuating member and the at least one axial offset transmission.

This application claims the priority of German Patent Document No. 10206 200.5, filed Feb. 15, 2002, the disclosure of which is expresslyincorporated by reference herein.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a toroidal variable-speed drive unit.

DE 101 22 176 A1 discloses such a toroidal variable-speed drive unit.This toroidal variable-speed drive unit is arranged within thetransmission case of a motor vehicle transmission and has two toroidalchambers, each with two rollers. The torque is transmitted in acontinuously variable manner by means of these rollers. Each of the tworollers is

fastened to a supporting journal,

rotatable about its own axis of rotation, and

supported fixedly in terms of rotation with respect to a pivot axis ofthe supporting journal which is perpendicular to its own axis ofrotation.

The two supporting journals form, in diagrammatic terms, the two laterallines of a parallelogram. The upper and the lower line of theparallelogram are formed by two rockers, the central bearing receptacleof which is supported with respect to the transmission case. An axialforce can be introduced into the supporting journals by means ofactuating members, so that the angles of the parallelogram change. Theangular movement of the parallelogram is in this case made technicallypossible in that the two rockers receive the supporting journals bymeans of articulated pivot bearings which allow a slight angularmovement.

DE 199 47 851 A1 also discloses a toroidal variable-speed drive unit.

An object of the invention is to provide a cost-effective andnevertheless highly fail-safe toroidal variable-speed drive unit.

The high fail-safety is achieved advantageously in that, in addition tothe “force synchronization,” typical of toroidal transmissions, whichconstantly holds all the rollers in the correct pivot-angle positionduring the operation of the toroidal variable-speed drive unit, “pathsynchronization” ensures operation. In this “path synchronization,”according to the invention, the supporting journals are received onlywith one side in a rocker. By contrast, on their other side, thesupporting journals are supported with respect to the transmission caseor to a component connected firmly to the transmission case.

This “rocker-free” support of the supporting journals in a bearingreceptacle which is fixed in terms of movement with respect to thetransmission case is advantageously particularly cost-effective. Thus,the articulated ends of the supporting journals can be received directlyin bearing bores or plain-bearing bushes in the transmission case. Thisis accompanied by the advantages of a reduction in the diversity ofparts.

Furthermore, a supporting plate connected fixedly in terms of movementto the transmission case may be provided for receiving the bearing boresor plain-bearing bushes. As a result, in a particularly advantageousway, the transmission case may consist of light, but also soft lightmetal, whilst the high forces occurring when the toroidal variablehigh-speed drive unit is in operation are supported in the supportingplate made from steel or cast iron.

Additionally, an embodiment of the invention allows an optimumfunctioning of the toroidal variable high-speed drive unit, in that thefriction to be overcome in order to pivot the supporting journal aboutits own pivot axis is kept low by means of a rolling bearing. In aparticularly advantageous way, the coefficient of friction between aconvex rolling-bearing outer ring of this rolling bearing and a linearplain bearing may be designed in such a way that, in the case of anunchanged transmission ratio of the toroidal variable high-speed driveunit, the static-friction limit is not exceeded over a period of time,so that there are also no translational axial fluctuations of thesupporting journal. By contrast, when a transmission ratio adjustment ofthe toroidal variable-speed drive unit, that is to say an axialdisplacement of the supporting journal, is specifically initiated, thestatic friction is exceeded and, because of the low sliding friction inthe linear plain bearing, scarcely any wear occurs.

In an embodiment of the invention, in addition to “forcesynchronization” and to “path synchronization,” what may be referred toas “angle synchronization” ensures to a particular extent that therollers of the toroidal variable-speed drive unit are in the correctpivot-angle position in relation to one another. This “anglesynchronization” ensures the correct pivot-angle position of the rollersin relation to one another even when the toroidal variable-speed driveunit is not in operation and the rollers are nevertheless shaken about.This situation arises, for example, when the motor vehicle is towed awayor is transported on a railway wagon.

In general, one advantage of power-split motor vehicle transmissionswith a toroidal variable-speed drive unit is that, as a result of theuse of a power path with a constant step-up, the toroidal variable-speeddrive unit is relieved within wide operating ranges. This relief isadvantageous particularly in the case of high-torque engines, in whichthe power take-off torque of the engine is markedly above the maximumpermissible input torque of the toroidal variable-speed drive unit andtherefore a reduction in the torque of the variable-speed drive unitsolely by the preselection of a step-up stage into high speed would notbe sufficient. The said high-torque engines are conventionally installedlongitudinally in drive trains.

Moreover, along with the corresponding design of the motor vehicletransmission, the relief of the toroidal variable-speed drive unit givesrise advantageously to an improvement in the overall efficiency of themotor vehicle transmission in the corresponding driving range, since thepower in the power path having a constant step-up can be transmittedwith higher efficiency than in that having a continuously variablestep-up.

A further advantage of the relief of the toroidal variable-speed driveunit is that the pressure forces at the driving/driven discs can therebybe lowered, thus leading to a lowering of the frictional losses. As aresult of the reduction in the frictional losses, less heat also has tobe discharged.

Furthermore, by the toroidal variable-speed drive unit being relieved,its useful life can be increased in an advantageous way.

One advantage of apportioning the transmission step-up to at least twodriving ranges is that the spread of the motor vehicle transmission isincreased.

Transmission spreads which are greater than the spread of the toroidalvariable-speed drive unit thus become possible.

Both driving ranges can advantageously be implemented in the power-splitmode, in order to increase the efficiency.

By means of a geared-neutral function, there is advantageously no needfor a starting element, such as, for example, a hydrodynamic torqueconverter. The implementation of a geared-neutral mode makes it possibleto have operation in which the driving states forward travel, reversetravel and standstill can be achieved solely by the adjustment of thetoroidal variable-speed drive unit. Furthermore, there is no need for areversing unit, such as, for example, a turning set with associatedclutches or brakes, which likewise has an advantageous effect on weight,construction space and costs.

The motor vehicle transmission is used in a particularly advantageousway in a drive train with a front engine and a rear-axle drive.Furthermore, the motor vehicle transmission is used in a particularlyadvantageous way in an all-wheel drive which emanates from a modifieddrive train with a front engine and with a rear-axle drive. Such a drivetrain is shown in DE 101 33 118.5 which has not already been published.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagrammatic axial section through a motor vehicletransmission which comprises a continuously variable toroidaltransmission, an intermediate planetary transmission and a finalplanetary transmission;

FIG. 2 shows a detailed sectional illustration of a detail II of thetransmission diagram from FIG. 1, this having, inter alia, websextending outwards in a radiating manner;

FIG. 3 shows a section through one of the webs from FIG. 2 in a detail;

FIG. 4 shows a basic diagrammatic section to explain the function of therollers of the toroidal variable-speed drive unit according to FIG. 1;

FIG. 5 shows, in a first alternative embodiment of a roller, the latterand its supporting journal in detail in a sectional illustration; and

FIG. 6 shows, in a second alternative embodiment of a roller, the latterand its supporting journal in detail in a sectional illustration.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagrammatic axial section through a motor vehicletransmission which comprises a continuously variable toroidalvariable-speed drive unit 7, an intermediate planetary transmission 8and a final planetary transmission 9.

The motor vehicle transmission is used in a drive train with a frontengine and with a rear-axle drive. The motor vehicle transmission isthus arranged in the force flux between the front engine, notillustrated in any more detail, and a rear-axle transmission, by meansof which rear drive shafts and consequently driving wheels are driven.The front engine is coupled to an input shaft 5 of the motor vehicletransmission and the rear-axle transmission is connected fixedly interms of rotation by means of a cardan shaft to an output shaft 6 forthe motor vehicle transmission.

By means of a friction clutch K3 arranged at the rear end of the motorvehicle transmission, the input shaft 5 can be coupled frictionally tothe output shaft 6, so that a direct drive-through from the engine tothe rear-axle transmission can be effected.

The input shaft 5 is mounted at its two end regions, by means of tworolling bearings 135 and 136, rotatably with respect to a non-rotatingcase part 26 of the motor vehicle transmission. In this case, the tworolling bearings 135 and 136 are designed as afixed-bearing/loose-bearing pairing. The input shaft 5 is connectedfixedly in terms of movement to an adjacent first toroidal centraldriving disc 11 of the toroidal variable-speed drive unit 7 and, via thecoaxial central input shaft 5, to a double-web planet carrier 18 of theintermediate transmission 8. This planet carrier 18 is connected fixedlyin terms of rotation to the second central toroidal driving disc 12,arranged adjacently to the latter, of the toroidal variable-speed driveunit 7. The two driving discs 11 and 12 are thus connected in parallelin the force flux or fixedly in terms of rotation relative to oneanother. A concentric intermediate shaft 14 which is arranged coaxiallyto the input shaft 5 and through which the latter passes with play isconstructed fixedly in terms of rotation with an axially central drivendisc 10. This driven disc 10 has worked into it, on its sides facingaxially away from one another, the two concave toroidal driven surfaces16 and 17. The driven disc 10 is connected fixedly in terms of movementto an inner central wheel 19 of the intermediate transmission 8.

A driving disc 11 or 12 is in frictional contact with its associateddriven surface 16 or 17 via two planets, which are known as rollers 13a, 13 b or 15 a, 15 b. In each case two rollers 13 a, 13 b or 15 a, 15 bare assigned to one of two toroidal chambers 93, 94. As explained inmore detail further below with regard to FIG. 4, the rollers 13 a, 13 bor 15 a, 15 b are in each case both rotatable about their own axis ofrotation 95 a, 95 b or 96 a, 96 b and pivotable about a pivot axisperpendicular to their own axis of rotation 95 a, 95 b.

The inner central wheel 19 of the intermediate transmission 8 has adrive connection 20 to an inner central wheel 21 as a first transmissionmember of the final transmission 9.

This drive connection 20 contains main planets 46 mounted on one web ofthe planet carrier 18 of the intermediate transmission 8 and havingtoothed rims 43 a, 43 b which are arranged on both sides of a radialdrive web of the planet carrier 18 and of which one toothed rim 43 ameshes with the inner central wheel 19 connected to the concentricintermediate shaft 14 and the other toothed rim 43 b meshes with asecond inner central wheel 48 which is arranged axially on the otherside of the radial drive web and which finally, in turn, has a driveconnection 51, containing an engageable and disengageable clutch K2, tothe inner central wheel 21 forming the first transmission member of thefinal transmission 9.

The toothed rim 43 a of the main planet 46, the said toothed rim meshingwith the one inner central wheel 19 of the intermediate transmission 8,is additionally in meshing engagement with a secondary planet 63 whichis mounted on the second web of the planet carrier 18 and, in turn,meshes with an outer central wheel 22 which is connected fixedly interms of rotation via a pot-shaped drive connection 23 to one clutchhalf of an engageable and disengageable friction clutch K1. A secondclutch half of this friction clutch K1 is connected fixedly in terms ofrotation to an outer central wheel 24 forming a second transmissionmember of the final transmission 9.

The final transmission 9 has a third transmission member in the form ofa planet carrier 25 which is connected fixedly in terms of rotation tothe non-rotating case part 26 of the motor vehicle transmission by meansof a radial supporting web 36 and which supports planet wheels 34 a, 34b with two toothed rims 37 a, 37 b having the same number of teeth,which are arranged on both sides of the supporting web 36 and of whichone toothed rim 37 a adjacent to the intermediate transmission 8 meshesboth with the inner and with the outer gearwheel 21 and 24.

The final transmission 9 has a fourth transmission member in the form ofa second outer central wheel 27 which meshes with the other toothed rim37 b of the planet wheels 34 b and which has a drive connection 28 tothe output shaft 6.

A parking-lock wheel 33 is arranged concentrically and fixedly in termsof movement on the outer circumference of the outer central wheel 27.

In the lower driving range, in forward travel the clutch K1 is engagedand the clutch K2 disengaged, so that the power is split at theintermediate transmission 8, a first part of the power flowing to thepower take-off shaft 6 and a second part of the power flowing via thetoroidal variable-speed drive unit 7 into the drive shaft 5.

FIG. 2 shows a detailed sectional illustration of a detail II of thetransmission diagram from FIG. 1, although the rollers 13 b, 15 b fromFIG. 1 are not illustrated.

The input shaft 5 has a first axial region 54, in which the toroidalvariable-speed drive unit 7 or the driving and driven discs 10, 11, 12are also located. This first axial region 54 is designed as a solidshaft, with the result that its diameter is very small. This first axialregion 54 is followed by a second axial region 34, in which a firstwheel-set plane of the intermediate transmission 8 also lies, the saidwheel-set plane comprising, inter alia,

the inner central wheel 19,

the toothed rim 43 a, and

the secondary planet 63.

Two oil ducts 56 a, 56 b are drilled obliquely into the solid shaft inthis second axial region 34. These oil ducts 56 a, 56 b issue, on theone hand, into an annular space 58 and, on the other hand, into acentral bore 57 of the input shaft 5, the said central bore lyingessentially in a third axial region 55. The two oil ducts 56 a, 56 bthus make a flow connection between the central bore 57 which is underoil pressure and the annular space 58 which lies essentially in thefirst axial region 54. Whilst the radially inner wall of the annularspace 58 is formed by the input shaft 5, the radially outer delimitationof the annular space 58 is formed by the concentric intermediate shaft14 designed as a hollow shaft. Orifices for the outflow of lubricatingoil from the annular space 58 lie at bearing points which are designedas the following rolling bearings:

-   a) a first needle bearing 50 for the rotatable support of the driven    disc 10 with respect to the input shaft 5,-   b) a single-row grooved ball bearing 60 for the axial and radial    mounting of the intermediate shaft 14 with respect to a case part 62    of the motor vehicle transmission,-   c) a second needle bearing 61 for the rotatable support of the    second central toroidal driving disc 12 with respect to the    intermediate shaft 14, and-   d) a third needle bearing 85 for the radial support of the central    wheel 19 with respect to the input shaft 5 in the second region 34.

a) to c) are explained in more detail below.

a) The first needle bearing 50 comprises rolling bodies which arearranged within a cage 64 and roll on the input shaft 5 in a region inwhich the latter is designed as a solid shaft. The cage 64 is insertedinto a central bore of the driven disc 10 and bears axially, on the onehand, against an end face 65 of one end 70 of the intermediate shaft 14.On the other hand, the cage 64 bears axially against an axial securingring 66 which is inserted into an inner groove at one axial end of thedriven disc 10. At the other axial end of the driven disc 10, the latteris screwed to an externally threaded sleeve 68, of which the radiallyoutward-projecting end collar bears axially against an end face of thedriven disc 10. Axially between the first needle bearing 50 and theexternally threaded sleeve 68, the driven disc 10 is connected fixedlyin terms of rotation to the intermediate shaft 14 by means of asplined-shaft toothing 67. In this case, a slight axial play is allowedbetween the cage 64 and the end face 65 or between the externallythreaded sleeve 68 and an external toothing 69, associated with thesplined-shaft toothing 67, of the input shaft 5.

The lubrication of the large needle bearing 50 takes place by means oflubricating oil which emerges, past a sealing ring 190 functioning as avirtual throttle, from the annular space 58 at the end 70 of theintermediate shaft 14.

b) The grooved ball bearing 60 has a bearing outer ring which is securedin the axial direction with respect to the case part 62, on the onehand, at a step 71 and, on the other hand, at an axial securing ring 72which is inserted into an inner groove of the case part 62.

In a similar way, a bearing inner ring of the grooved ball bearing 60 issecured in the axial direction with respect to the intermediate shaft14, on the one hand, at a step 73 and, on the other hand, at an axialsecuring ring 74 which is inserted into a circumferential groove of theintermediate shaft 14.

The lubrication of the grooved ball bearing 60 takes place by means oflubricating oil which emerges from the annular space 58 through anoblique bore 75 in the intermediate shaft 14. This bore 75 is arrangedaxially next to the grooved ball bearing 60 and is directed towards therolling body of the latter.

c) The second needle bearing 61 comprising rolling bodies which arearranged within a cage 76 and roll on the intermediate shaft 14. Thecage 76 is pressed into a central bore of the driven disc 12 and bearsaxially against an end face 77 of a bore bottom of this central bore.

An oblique bore 79, which supplies the second needle bearing 61 withlubricating oil, is drilled into the intermediate shaft 14 radiallywithin the driven disc 12 and axially next to the second needle bearing61.

As a consequence of the system, the driven disc 12 is fixed in terms ofrotation and axially prestressed with respect to a planet-carrier boltreceptacle 80 of the planet carrier 18 by means of an axial toothing 82and a cup spring 81.

The annular space 58 is sealed off, on its side facing the intermediatetransmission 8, by means of a sealing ring 83 which is inserted into aconcentric bore of the central wheel 19 produced in one part with theintermediate shaft 14 and which functions as a virtual throttle in thatthe sealing ring 83 allows a defined leakage. The sealing ring 83 issecured by means of a cage 84 of the third needle bearing 85. Thesealing ring 83 bears with its inside against the input shaft 5 axiallynext to the two oil ducts 56 a, 56 b and allows the defined leakagethroughflow for the supply of lubricant to the third needle bearing 85,whilst maintaining a lubricant pressure in the annular space 58.

A planet-carrier arm 86 extends radially outwards in the third region 55axially next to the central wheel 19. This planet-carrier arm 86 haswebs 87 which extend outwards in a radiating manner and which areinterrupted circumferentially by recesses 88. The main planets 46 passthrough these recesses 88, so that the toothed rims 43 a, 43 b areadjacent to the planet-carrier arm 86 on both sides.

FIG. 3 shows, in a detail, a section through one of the webs 87extending outwards in a radiating manner. The webs 87 are designedidentically, and therefore only one of the three webs 87 distributeduniformly on the circumference is explained below.

The web 87 has, radially on the outside, a bore 89 which is orientedparallel to a central axis 52, also evident in FIG. 1 and FIG. 2, of themotor vehicle transmission and into which a planet-carrier bolt 90 ofthe secondary planet 63 is inserted with a press fit. This press fit islocated centrally on the planet-carrier bolt 90, so that the latterprojects axially with an end region 91 facing the toroidalvariable-speed drive unit 7 and with an end region 92 facing away fromthe latter. The planet-carrier bolt 90 has on the end region 92 facingaway, radially on the inside, a long hole which issues into a centralconcentric blind-hole bore. This blind-hole bore is closed at its accessorifice by means of a ball. At the bottom of the blind-hole bore, thesaid bottom being located in the other end region 91, there is, in theplanet-carrier bolt 90, a transverse bore which makes a flow connectionfrom the blind-hole bore to a needle mounting of the secondary planet63.

Arranged radially inwards from the planet-carrier bolt 90 is the secondinner central wheel 48 which meshes with the toothed rim 43 b notevident in the drawing plane of FIG. 3. This central wheel 48, whichrotates during driving, throws radially outwards, as a result of thecentrifugal force, lubricating oil of which a fraction passes through

the long hole,

the blind-hole bore and

the transverse bore

to the needle mounting of the secondary planet 63, so that the saidneedle mounting is always lubricated and cooled in a low-friction andfail-safe manner.

FIG. 4 shows a basic diagrammatic section through the rollers 13 a, 13 bof the first toroidal chamber 93 and the rollers 15 a, 15 b of thesecond toroidal chamber 94 of the toroidal variable-speed drive unit 7according to FIG. 1. For the sake of greater clarity, the driving discsand driven disc are not illustrated. The basic diagrammatic section isillustrated in the actual installation position of the motor vehicletransmission, so that components lying below in the installationposition are designated hereafter as being arranged “below” andcomponents lying above in the installation position are designatedhereafter as being arranged “above.”

Since the four rollers 13 a, 13 b, 15 a, 15 b of the two toroidalchambers 93, 94 are designed essentially identically and have identicalfunctioning, the common features are first explained hereafter withreference to the rollers 13 a, 13 b of one toroidal chamber 93.

The two rollers 13 a, 13 b are both rotatable about their own axis ofrotation 95 a, 95 b and pivotable about a pivot axis 97 a, 97 bperpendicular to their own axis of rotation 95 a, 95 b. For thispurpose, each of the rollers 13 a, 13 b is mounted rotatably about itsown axis of rotation 95 a, 95 b by means of two bearings 98 a or 98 band 99 a or 99 b on an eccentric journal 100 a or 100 b which isarranged by means of a thrust-type needle bearing 101 a or 101 b so asto be slightly pivotable about a further pivot axis 102 a or 102 barranged, offset, parallel to the axis of rotation 95 a or 95 b. In thiscase, the eccentric journal 100 a or 100 b is received, mounted byrolling bearings, pivotably about this further pivot axis 102 a or 102 bin a supporting journal 103 a or 103 b. This supporting journal 103 a or103 b extends perpendicularly to the axis of rotation 95 a, 95 b or tothe further pivot axis 102 a or 102 b and at its two ends 104 a, 105 aor 104 b, 105 b has rolling bearings with crowned bearing outer rings.These bearing outer rings or ends 104 a, 105 a or 104 b, 105 b arereceived, on the one hand, in bores 107 a or 107 b of a steel supportingplate 106 and, on the other hand, in bores 108 a or 108 b of a rocker109. Both the supporting plate 106 and a central rocker bearing 110 ofthe rocker 109 are connected fixedly in terms of movement to alight-metal transmission case 111 of the motor vehicle transmission.

The lower ends 108 a and 108 b of the supporting journals 103 a, 103 bare supported axially against pistons of hydraulic axial actuatingmembers 112 a, 112 b which are arranged below the supporting journal 103a, 103 b. The cylinders of the hydraulic axial actuating members 112 a,112 b are supported axially with respect to the said light-metaltransmission case 111 in a way not illustrated in any more detail. Belowthe hydraulic axial actuating members 112 a, 112 b is arranged anelectrohydraulic control plate, not illustrated in any more detail, ofthe motor vehicle transmission. This control plate has solenoid valvesand control slides for controlling or regulating the clutches K1, K2, K3and the axial actuating members 112 a, 112 b.

The torque transmission of the toroidal variable-speed drive unit 7takes place by the rotation of the rollers 13 a, 13 b about their ownaxis of rotation 95 a, 95 b. By contrast, the transmission ratio of thetoroidal variable-speed drive unit 7 is adjusted by pivoting about thepivot axis 97 a, 97 b.

Reference is made below, once again, to the two toroidal chambers 93 and94.

To initiate the abovementioned pivoting about the pivot axes 97 a, 97 b,113 a, 113 b, the axial actuating members 112 a and 114 a or 112 b and114 b are acted upon by hydraulic pressure. At the same time, in eachcase, the pistons located on the same side are acted upon by pressure.During this action of pressure, all four rollers 13 a, 15 a, 13 b, 15 bpivot about their pivot axes 97 a, 97 b as a result of the forces actingat the rolling points between the rollers 13 a and 15 a or 13 b and 15 band the driving/driven disc 10, 11, 12 of the toroidal variable-speeddrive unit 7, until a force equilibrium has been established again atthe rollers 13 a, 15 a, 13 b, 15 b and axial actuating members 112 a,114 a, 112 b, 114 b. Thus, by means of the new pivot-angle positionabout the pivot axes 97 a, 97 b, 113 a, 113 b, a new transmission ratioof the toroidal variable-speed drive unit 7 is set continuously andwithout any interruption in traction.

As a result of the identical hydraulic supporting forces and similarfrictional forces and therefore similar forces in rolling contact, allfour rollers 13 a, 13 b, 15 a, 15 b assume the same pivot-angle positionin terms of amount with regard to their four pivot axes 97 a, 97 b, 113a, 113 b, their arrangement being symmetrical to one another. Thisorientation of the pivot-angle position of the rollers in relation toone another, which is achieved in this way, is designated as what may bereferred to as “force synchronization.”

In the event of the abovementioned hydraulic pressure change at the twoaxial actuating members 112 a, 114 a or 112 b, 114 b of one side, therocker 109 pivots, since the two supporting journals 103 a, 116 a or 103b, 116 b are displaced axially with respect to their pivot axes 97 a,113 a or 97 b, 113 b, and, between their lower bearing outer rings andthe rocker 109, friction occurs in the region of their bores 108 a, 118a or 108 b, 118 b. As a result of the articulated crowned receptacle,the angle between the rocker 109 and the supporting journals 103 a, 103b, 116 a, 116 b changes. Owing to these changed geometric conditions,all four rollers 13 a, 13 b, 15 a, 15 b have forced upon them a pathleading to a pivot-angle position in which the rollers 13 a, 13 b, 15 a,15 b are arranged symmetrically to one another. This secondsynchronization ensuring safety in addition to the “forcesynchronization” is designated as what may be referred to as “pathsynchronization.”

The toroidal variable-speed drive unit 7 has, in addition to these twosynchronizations, a third synchronization which, even with the inputshaft 5 at a standstill, ensures the abovementioned symmetricalarrangement of all the supporting journals 103 a, 103 b, 116 a, 116 b ofthe rollers 13 a, 13 b, 15 a, 15 b to one another. This synchronization,designated as what may be referred to as “angle synchronization,” takesplace by means of four belts 119, 120, 121, 122 which connect to oneanother, on the one hand, the two supporting journals 103 a and 103 b or116 a and 116 b belonging to a toroidal chamber 93 or 94 and, on theother hand, the two supporting journals 103 a and 116 a or 103 b and 116b arranged on the respective side, that is to say on the right or on theleft. The four belts 119, 120, 121, 122 are in this case each simplylooped crosswise, in order to bring about a reversal of direction ofrotation during the pivoting of the supporting journals 103 a, 103 b,116 a, 116 b. The four supporting journals 103 a, 103 b, 116 a, 116 bhave, between their upper ends and their middle region in which therollers 13 a, 13 b, 15 a, 15 b are arranged, two take-up discs 123, 124,125, 126, 127, 128, 129, 130 arranged axially adjacently with respect tothe pivot axes 97 a, 97 b, 113 a, 113 b. The four belts 119, 120, 121,122 are looped in each case around two of these take-up discs, the twobelts 119, 120 associated with the individual toroidal chambers 93 and94 being arranged in a lower plane, and the two belts 121, 122connecting the supporting journals 103 a, 103 b, 116 a, 116 b of the twotoroidal chambers 93 and 94 being arranged in an upper plane.

FIG. 5, in a first alternative embodiment of a roller 1013 a, shows thelatter in detail in a sectional illustration.

The roller 1013 a is both rotatable about its own axis of rotation 1095a and pivotable about a pivot axis 1097 a perpendicular to its own axisof rotation 1095 a. For this purpose, the roller 1013 a is mounted bymeans of two bearings 1098 a and 1099 a rotatably about its own axis ofrotation 1095 a on an eccentric journal 1100 a which, by means of athrust-type needle bearing 1101 a, is arranged so as to be slightlypivotable about a further pivot axis 1102 a arranged, offset, parallelto the axis of rotation 1095 a. In this case, the eccentric journal 1100a is received, mounted by rolling bearings, pivotably about this furtherpivot axis 1102 a in a supporting journal 1103 a. This supportingjournal 1103 a is bulged out in a middle region. The roller 1013 a isarranged in this middle region. The supporting journal 1103 a extendsessentially perpendicularly to the axis of rotation 1095 a or to thefurther pivot axis 1102 a and at its two ends 1104 a, 1105 a has needlebearings with bearing outer rings 1140, 1141 designed to be crowned onthe outside. The upper bearing outer ring 1140 is received in a bore1107 a of a steel supporting plate 1106 and the lower bearing outer ring1141 is received in a bore 1108 a of a rocker 1109. Both the supportingplate 1106 and a bearing receptacle, not illustrated in any more detail,of the rocker 1109 are connected fixedly in terms of movement to alight-metal transmission case, not illustrated in any more detail, ofthe motor vehicle transmission.

The supporting journal 1103 a is provided, above the upper needlebearing, with a journal 1150 which is designed coaxially with the pivotaxis 1097 a and which is connected fixedly in terms of rotation andaxially non-displaceably to a take-up disc 1151 by means of asplined-shaft toothing and a shaft securing ring. Looped around thistake-up disc 1151 is a toothed belt 1153 which connects the supportingjournal 1103 a illustrated to a supporting journal, not evident in FIG.5, of the same toroidal chamber. The belt 1153 is in this case simplylooped crosswise, so that the supporting journal, not evident, of thesame toroidal chamber always rotates in the opposite direction.

Between the lower needle bearing and the roller 1013 a, the supportingjournal 1103 a is produced in one part with a take-up disc 1154. A belt1155 is simply looped crosswise around this take-up disc 1154 andconnects the supporting journal 1103 a illustrated to a supportingjournal, not evident in FIG. 5, of a second toroidal chamber, in such away that the supporting journal of the second toroidal chamber alwaysrotates in the opposite direction.

The supporting journal 1103 a is provided, below the lower needlebearing, with a journal 1152 which is designed coaxially to the pivotaxis 1097 a and which is supported axially on a hydraulic axialactuating member not illustrated in any more detail. Below thishydraulic axial actuating member is arranged an electrohydraulic controlplate, not illustrated in any more detail, for the control of the axialactuating member, of further axial actuating members and of clutchesaccording to FIG. 1.

FIG. 6, in a second alternative embodiment of a roller, shows the latterin detail in a sectional illustration.

The roller 2013 a and the supporting journal 2103 a are designed inbroad parts in a similar way to the roller of the first alternativeembodiment, and therefore only the essential differences are dealt withbelow.

Instead of a take-up disc arranged above an upper needle bearing, thesupporting journal 2103 a is produced, in a region between the upperneedle bearing and the roller 2013 a, in one part with a take-up disc2151. Looped around this take-up disc 2151 is a belt 2153 which connectsthe supporting journal 2103 a illustrated to a supporting journal, notevident in FIG. 6, of the same toroidal chamber. The belt 2153 is inthis case simply looped crosswise, so that the supporting journal, notevident, of the same toroidal chamber always rotates in the oppositedirection.

The bearings for mounting the supporting journal may also be designed asbarrel-shaped bearings, in which case a crowned bearing outer ring isdispensed with and the barrel-shaped rolling bodies are arrangeddirectly in the bores of the rocker and the bores of the supportingplate.

Furthermore, instead of the bores for receiving the bearing outer rings,linear bearings may be provided both in the supporting plate and in therocker.

The take-up discs or the belts which connect the supporting journals toone another perform the function of an axial offset transmission.Consequently, for codirectional torque transmission with a transmissionratio of 1:1, the supporting journals may also be connected via an oddnumber of gearwheels, by means of toothed belts, by means of linkages orelse by means of slotted guides.

Instead of the two oil ducts, any number of oil ducts offsetcircumferentially, at an angle or radially may be drilled into the solidshaft. If appropriate, a single oil duct may be sufficient.

Instead of the oblique bore, illustrated in FIG. 1, in the intermediateshaft for the supply of lubricating oil to the grooved ball bearing, abore may also be provided which is oriented transversely to the centralaxis and which is directed towards an oil baffle of the grooved ballbearing.

Instead of the two sealing rings, illustrated in FIG. 2, which functionas a virtual throttle, the intermediate shaft designed as a hollow shaftand the input shaft arranged within the latter may be provided with afit. Then, instead of the sealing rings, the fit functions as a virtualthrottle.

The illustrated clutches for selecting the driving range may be designedas a friction clutch, as a positive clutch, such as, for example, a clawclutch, or as a combined friction and positive clutch, such as, forexample, a synchronizing device.

In particular, the clutch arranged at the rear end of the motor vehicletransmission may be designed, for the purpose of direct drive-through,as a friction clutch or as a positive clutch or, alternatively, as acombined positive and friction clutch.

The illustrated coaxial motor vehicle transmission with a continuouslyvariable toroidal variable-speed drive unit and with a geared-neutralfunction is appropriate, furthermore, for all-wheel drive, such as isillustrated in DE 101 33 118.5. In this case, the transmission take-offshaft may be followed by a power divider for all-wheel drive.

Depending on the construction space available in the axial direction ofthe drive train, the motor vehicle transmission may have any number ofdriving ranges. In this case, one driving range may be designed as adirect gear, in which the engine rotational speed is conducted directlyto the transmission take-off shaft, without any meshing engagement ofgearwheels, so that particularly high efficiency is achieved. Inparticular, such a direct gear is appropriate in vehicles with aconsumption characteristic diagram having a flat profile, that is to saywith low consumption over a wide rotational speed range.

Further power-split driving ranges which have additional planet sets andclutches are appropriate.

The motor vehicle transmission may have an input step-up stage which,however, makes it possible to have selectively a step-up to high speedor to a low speed.

The parking-lock wheel shown in FIG. 1 may be arranged in alternativeembodiments at any desired point on the output shaft.

The embodiments described are merely exemplary embodiments. Acombination of the features described for different embodiments islikewise possible. Further, in particular undescribed features of thedevice parts belonging to the invention may be gathered from thegeometries, illustrated in the drawings, of the device parts.

The foregoing disclosure has been set forth merely to illustrate theinvention and is not intended to be limiting. Since modifications of thedisclosed embodiments incorporating the spirit and substance of theinvention may occur to persons skilled in the art, the invention shouldbe construed to include everything within the scope of the appendedclaims and equivalents thereof.

1. A toroidal variable-speed drive unit arranged within a transmissioncase, the unit comprising: at least one toroidal chamber including atleast two rollers, each of the at least two rollers is rotatable aboutits own axis of rotation; a supporting journal for each of the at leasttwo rollers, wherein each roller is supported fixedly in terms ofrotation with respect to a pivot axis of the supporting journal which isperpendicular to its own axis of rotation; and first and second bearingsfor each supporting journal, wherein each supporting journal is receivedpivotably and axially displaceably with respect to its pivot axis in thefirst and second bearings, wherein the first bearing is arranged in arocker, and wherein the second bearing includes a bearing receptaclewhich is fixed in terms of movement with respect to the transmissioncase.
 2. The toroidal variable-speed drive unit according to claim 1,wherein each roller is arranged between the first bearing and the secondbearing.
 3. The toroidal variable-speed drive unit according to claim 2,wherein each rocker includes a rocker bearing arranged centrally betweenthe two first bearings.
 4. The toroidal variable-speed drive unitaccording to claim 2, wherein the transmission case includes a lightmetal, wherein the unit further comprises a supporting plate which isconnected fixedly in terms of movement to the transmission case andwhich includes a steel or cast iron, and wherein the bearing receptaclesare arranged in the supporting plate.
 5. The toroidal variable-speeddrive unit according to claim 2, further comprising convexrolling-bearing outer rings, wherein the bearing receptacles are linearplain bearings and wherein the supporting journals are received in thelinear plain bearings in an articulated manner using the convexrolling-bearing outer rings.
 6. The toroidal variable-speed drive unitaccording to claim 2, further comprising axial offset transmissions,wherein the supporting journals of the toroidal chamber are coupled toone another with the axial offset transmissions.
 7. The toroidalvariable-speed drive unit according to claim 2, further comprising atleast one axial offset transmission and a second toroidal chamber whichis substantially similar to the first toroidal chamber, the supportingjournals of the second toroidal chamber are connected in atorque-transmitting manner to the supporting journals of the firsttoroidal chamber with the at least one axial offset transmission.
 8. Thetoroidal variable-speed drive unit according to claim 2, furthercomprising axial actuating members, wherein the supporting journals canbe supported at one end on the axial actuating members, the rocker beingarranged between these axial actuating members and the rollers, whereinthe bearing receptacle arranged fixedly in terms of movement withrespect to the transmission case is arranged at the other end of thesupporting journals.
 9. The toroidal variable-speed drive unit accordingto claim 1, wherein each rocker includes a rocker bearing arrangedcentrally between the two first bearings.
 10. The toroidalvariable-speed drive unit according to claim 1, wherein the transmissioncase includes a light metal, wherein the unit further comprises asupporting plate which is connected fixedly in terms of movement to thetransmission case and which includes a steel or cast iron, and whereinthe bearing receptacles are arranged in the supporting plate.
 11. Thetoroidal variable-speed drive unit according to claim 1, furthercomprising convex rolling-bearing outer rings, wherein the bearingreceptacles are linear plain bearings and wherein the supportingjournals are received in the linear plain bearings in an articulatedmanner using the convex rolling-bearing outer rings.
 12. The toroidalvariable-speed drive unit according to claim 1, further comprising axialoffset transmissions, wherein the supporting journals of the toroidalchamber are coupled to one another with the axial offset transmissions.13. The toroidal variable-speed drive unit according to claim 1, furthercomprising a second toroidal chamber which is substantially similar tothe first toroidal chamber, the supporting journals of the secondtoroidal chamber are connected in a torque-transmitting manner to thesupporting journals of the first toroidal chamber (93) with at least oneaxial offset transmission.
 14. The toroidal variable-speed drive unitaccording to claim 1, further comprising axial actuating members,wherein the supporting journals can be supported at one end on the axialactuating members, the rocker being arranged between these axialactuating members and the rollers, wherein the bearing receptaclearranged fixedly in terms of movement with respect to the transmissioncase is arranged at the other end of the supporting journals.
 15. Amethod for making a toroidal variable-speed drive unit arranged within atransmission case, the method comprising: providing at least onetoroidal chamber that includes at least two rollers, each of the atleast two rollers is rotatable about its own axis of rotation; providinga supporting journal for each of the at least two rollers, andsupporting each roller fixedly in terms of rotation with respect to apivot axis of the supporting journal which is perpendicular to its ownaxis of rotation; providing first and second bearings for eachsupporting journal; placing each supporting journal pivotably andaxially displaceably with respect to its pivot axis in the first andsecond bearings; arranging the first bearing in a rocker; and fixing abearing receptacle of the second bearing in terms of movement withrespect to the transmission case.
 16. The method according to claim 15,further comprising arranging each roller between the first bearing andthe second bearing.
 17. The method according to claim 16, furthercomprising centrally arranging a rocker bearing of each rocker betweenthe two first bearings.
 18. The method according to claim 16, whereinthe transmission case includes a light metal, the method furthercomprising connecting fixedly a supporting plate, which includes a steelor cast iron, in terms of movement to the transmission case and, andarranging the bearing receptacles in the supporting plate.
 19. Themethod according to claim 16, further comprising convex rolling-bearingouter rings, wherein the bearing receptacles are linear plain bearingsand wherein the supporting journals are received in the linear plainbearings in an articulated manner using the convex rolling-bearing outerrings.
 20. The method according to claim 16, further comprising couplingthe supporting journals of the toroidal chamber to one another withaxial offset transmissions.
 21. The method according to claim 16,further comprising providing a second toroidal chamber which issubstantially similar to the first toroidal chamber, and connecting thesupporting journals of the second toroidal chamber in atorque-transmitting manner to the supporting journals of the firsttoroidal chamber with at least one axial offset transmission.
 22. Themethod according to claim 16, further comprising supporting thesupporting journals at one end on axial actuating members, arranging therocker between these axial actuating members and the rollers, andarranging the bearing receptacle arranged fixedly in terms of movementwith respect to the transmission case at the other end of the supportingjournals.
 23. The method according to claim 15, further comprisingcentrally arranging a rocker bearing of each rocker between the twofirst bearings.
 24. The method according to claim 15, wherein thetransmission case includes a light metal, the method further comprisingconnecting fixedly a supporting plate, which includes a steel or castiron, in terms of movement to the transmission case and, and arrangingthe bearing receptacles in the supporting plate.
 25. The methodaccording to claim 15, further comprising convex rolling-bearing outerrings, wherein the bearing receptacles are linear plain bearings andwherein the supporting journals are received in the linear plainbearings in an articulated manner using the convex rolling-bearing outerrings.
 26. The method according to claim 15, further comprising couplingthe supporting journals of the toroidal chamber to one another withaxial offset transmissions.
 27. The method according to claim 15,further comprising providing a second toroidal chamber which issubstantially similar to the first toroidal chamber, and connecting thesupporting journals of the second toroidal chamber in atorque-transmitting manner to the supporting journals of the firsttoroidal chamber with at least one axial offset transmission.
 28. Themethod according to claim 15, further comprising supporting thesupporting journals at one end on axial actuating members, arranging therocker between these axial actuating members and the rollers, andarranging the bearing receptacle arranged fixedly in terms of movementwith respect to the transmission case at the other end of the supportingjournals.